Biology and Etiology of Rare Pediatric Tumors

Abstract

Different malignant tumor types occur in children compared to adults. While in childhood we typically find leukemia, lymphoma, and various embryonal tumors, in adulthood, mainly gastrointestinal cancer, melanoma, malignancies of the head and neck, and lung and breast cancers occur. Not only tumor types and frequency differs, also the pathogenetic origin and genetic factors in malignant childhood tumors are unlike those in adult cancer. Cancer biology changes over age as the inner and outer circumstances at the time of cancer initiating mutation vary according to state of development. Neoplasia in childhood and adolescence are mainly based on an intrinsic system error – mislead development within embryogenesis. These are often very simple but specific DNA, chromosome, or genomic rearrangements. Epithelial tumors and other adult-type tumors like secondary leukemia on the other hand show more complex genetic alterations. A long history of carcinogenic and mutagenic exposition, as well as mislead differentiation, aging, and elimination processes are involved in carcinogenesis in adulthood. These differences might also explain why childhood cancer is more responsive to therapy than adult cancer (Haas 2004).